1. Field of the Invention
This invention relates generally to compositions and methods for combating kidney disease and particularly to the use of food compositions for preventing or treating kidney disease.
2. Description of the Prior Art
Chronic kidney disease currently affects as many as 20 million Americans. Unfortunately, the incidence and prevalence of the disease have doubled in the past few years. The increase is most likely attributable to improved treatments for hypertension, diabetes, and coronary disease. These improvements have increased the longevity for affected patients and, therefore, their likelihood of developing chronic kidney disease. Estimated medical and other economic costs of chronic kidney disease are expected to approach $28 billion annually within a few years.
The effect of dietary protein restriction on kidney disease is the subject of debate. Some studies suggest that dietary protein restriction slows the progression of kidney disease, particularly in patients with diabetes (Pedrini M T, Levey A S, Lau J, Chalmers T C, Wang P H. The effect of dietary protein restriction on the progression of diabetic and nondiabetic renal diseases: a meta-analysis. Ann Intern Med 1996; 124:627-32). However, these studies were inconclusive by the use of ACE-inhibitor therapy on the rate of disease progression. One study attempted to determine a level of protein intake that might reduce the risk of kidney disease progression and also minimize the risk of malnutrition (Klahr S, Levey A S, Beck G J, Caggiula A W, Hunsicker L, Kusek J W, et al. The effects of dietary protein restriction and blood-pressure control on the progression of chronic renal disease. Modification of Diet in Renal Disease Study Group. N Engl J Med 1994; 330:877-84). The study evaluated three levels of dietary protein intake and found that a very-low-protein diet slightly decreased the rate of progression of proteinuria compared with diets with higher protein intake. The very-low-protein diet did not result in malnutrition but it also did not decrease the progression of kidney disease.
Further, diets that contain very low amounts of protein and other nutrients may be beneficial for preventing or treating kidney disease but can cause undesirable weight loss and muscle wasting. In contrast, diets that have higher amounts of protein and other nutrients are generally not useful for preventing or treating kidney disease. Similarly, there is no useful information on the combination of nutrients that can be used to prevent or treat kidney disease. There is, therefore, a need for food compositions having defined ranges of protein and other nutrients that are beneficial for preventing or treating kidney disease while avoiding the undesirable weight loss and muscle wasting.